Work out percentage discounts instantly! - Free Educational videos for Students in K-12 | Lumos Learning

Work out percentage discounts instantly! - Free Educational videos for Students in k-12


Work out percentage discounts instantly! - By tecmath



Transcript
00:0-1 Welcome to take Math Channel . We're going to be
00:02 having a look at this video is we're going to
00:03 be looking about how to mentally take off a percentage
00:07 . Okay . And the reason for this is because
00:09 quite often you go into a shop , another horror
00:11 story and I'll have something like , You know ,
00:14 25% off this amount or 20% from this amount or
00:18 50% off this amount . And it's really handy to
00:20 be able to work out fairly quickly what's , what
00:23 this amount is with the least amount of hassle as
00:26 possible , I guess with the least amount of bother
00:28 . So this is going to be aimed at looking
00:30 at this . So there's a couple of concepts .
00:32 I'm going to be tying in together with this .
00:34 Okay . I'm trying to by the , make the
00:38 calculations as simple as possible . So Let's have a
00:42 look at this . And so you went to a
00:44 shop and something was , I started nice and easy
00:47 . Something was $20 and we wanted to take off
00:51 . Um What about we take off 20% . Now
00:57 look , you could work out 20% of 20 and
00:59 we could take that off . But there's a I
01:01 think it's really before we go on , it's really
01:03 important to get this idea what Taking off 20% is
01:06 because $20 itself is $20 is the original amount .
01:09 This is the 100% . 100% of the amount out
01:14 of 100 . This is 100% . We're taking off
01:17 20% . So this is the same as 100% ,
01:22 taking 20% , working at 80% of the number .
01:26 Okay , so straight away , when you said it's
01:28 taken by 80% if you take this 20 off ,
01:31 100 you won't realize that what you're actually working out
01:35 is rather than , you know , and this is
01:38 why the numbers are still simple . You're actually just
01:40 working at 80% of this number here . Okay ,
01:44 this is Okay , so this is where we take
01:47 20% off . Okay . You good with that ?
01:49 Yeah , this is gonna , so first off ,
01:51 that's a really big idea to get that . It's
01:53 a great idea . It's not too hard . That's
01:54 the first step . I recommend when we're doing the
01:57 next step , would all recommend ? Is this a
01:59 bit of a trick for working out percentages mentally ?
02:02 We've explored these in other videos as well . And
02:05 so this is as follows . So that's the idea
02:08 of 100% 50% 10% 5% to work this out really
02:20 quickly . And that's simple that they're very simple .
02:22 Okay . And I'll show you how Um so it's
02:25 100% is the whole number , so say $20 here
02:28 . 100% . He's 20 . 50% is half of
02:33 100 . Okay , so it's 1020 , which is
02:36 10 , we have 10% 100 divided by 10 .
02:43 So 1/10 of that . So all we're doing is
02:45 removing this this zero here . Okay . Or moving
02:49 this decimal place , someone . So this becomes to
02:52 20 , divided by 10 is too And the same
02:55 this uh 5% here , is this 50% divided by
02:59 10 or we're gonna move this decimal place . So
03:01 this becomes one . So you got this idea ?
03:03 That's pretty simple . Right ? So with 80 ,
03:06 we have a number of components that we could actually
03:08 make up 80 by going 50 10 , 10 ,
03:11 10 . Okay , at an early these together that's
03:14 the same . We're going to go 10 plus two
03:16 plus two plus two because this is the same as
03:18 80% . You get this idea , let's do it
03:22 . So to work out this , we're going Um
03:26 or even a simpler way , you might actually do
03:28 this in your first starting to this you might work
03:30 out 10% which is to And then there's 80% .
03:34 It's nearly eight lots of that . Okay , so
03:37 that's probably even a simpler way . We have 80
03:40 divided by , Sorry , 20 divided by 10 ,
03:45 Which is two times a day , which is 16
03:49 . Okay , So This is our answer . $16
03:53 . Now . This might have thrown you a little
03:55 bit . So , we're gonna go through a few
03:57 examples with this . All right there not too bad
03:59 . Once you get a once you get the hang
04:01 of them , so Let's give this another go .
04:08 So , so we had to say something like again
04:10 , we had a nice easy amount . Let's go
04:13 $40 this time . And I want to take off
04:17 uh at this time we take off 30 percent .
04:23 Okay . They will get a bit nastier . Okay
04:26 . So We're taking off 30% . But when you
04:28 realize really , really quickly is taking off 30% is
04:31 the same as working out how much 70% is 100
04:34 take away ? 30 or 70 . Yeah . So
04:36 this is we just want to know what 70% of
04:39 this number is . Okay , So the easiest way
04:42 working at 70% is we can work out what seven
04:45 lots of this 10% is . So 10% . Okay
04:49 , 100% of 40 . It's 40 . And that
04:53 divided by 10 is four and then seven fours we
04:57 get our answer . Oh , 28 . Okay .
05:00 So $28 . You good with this ? Okay .
05:07 Because Again , is 40 . 10% is four ,
05:13 and then 70 is seven lots of 10 to 74
05:16 28 . Okay . All right , let's work out
05:22 another one of these and this , by the way
05:25 , you don't need to have tattooed on your arm
05:27 , anything like this , You can mentally think there's
05:29 quite easily and trying to make them as simple as
05:32 you can . I think when you're doing okay ,
05:34 obviously . So what about we did say something like
05:37 and give this one to go before before I waffle
05:40 on and finish it . What about we do say
05:42 something of $50 and we wish to take off 25%
05:57 . Okay , this is a bit harder this time
05:59 . Yeah . Okay . So what we might work
06:01 out with this is we might realize that if we
06:03 first off , what what would you actually know is
06:06 we want to know what 75 of 50 years ?
06:09 Okay , So it's 75 percent of 15 , and
06:15 this can be made up a couple of ways .
06:17 Okay , We're gonna need Um seven of these tens
06:23 and one of these fives . Okay . So First
06:28 off , really quickly , what you might think is
06:29 10% of this is five and half of that's going
06:32 to be $2.50 . Okay . Because it's gonna be
06:35 the $5 listening to $2.50 bit , there's gonna be
06:38 a five bits of 75 to 35 Plus $3 50
06:44 is 30 $7.50 . I can't . How did you
06:52 go with that 1 ? All right . Now ,
06:55 look , I think it's that's probably the simplest way
06:58 of doing these , but a lot of these ,
06:59 I know we can get into uh 10% . We
07:02 get into more wonders than that . But a lot
07:03 of sales that were talking more , it's these very
07:07 uh 30% 25% of that sort of thing . Okay
07:11 , I might give that 25% another . Okay ?
07:14 In fact , no , let's go a step further
07:16 than this . Let's get a different number and we'll
07:21 go another one . Say what I wanted to do
07:24 is I want to get this time 17 dollars .
07:30 Let's go $72 , we can make it a little
07:33 bit harder and I want to take off this time
07:37 75% . Now , this is a more difficult one
07:41 . I think we all agree on this one .
07:42 Right ? So first off this 75% , we're going
07:45 to see that again as we're just working at 25%
07:50 of this amount . Okay , so this is to
07:54 lots of this and one lot of this . Okay
07:58 , so What we're going to be doing is we're
08:00 gonna be adding $7 , 20 And $3.60 . Can
08:06 you see that straight away ? So 7 20 plus
08:09 7 20 is $14.40 plus $3.60 is $18 now .
08:20 I just want to double check that one . Okay
08:22 so let's write this one down . Um So we
08:26 have 10% 10% this is $7.20 and This one is
08:31 going to be 360 . So we get to lots
08:35 of these which is 1440 Plus , this is 15
08:40 , Last three is $18 . Now look obviously the
08:43 more complex the numbers , the more complex the calculation
08:46 is going to be in your hand . They're gonna
08:47 get harder . So then you might employ things like
08:50 if they start to get really silly , maybe you
08:52 would look at this and say I like alcohol ,
08:53 that's 70 just to save myself mentally what's going on
08:56 and and then you'll be able to work it out
08:58 A little bit easier . So maybe you look at
08:59 this and had 70 and then you can go ,
09:01 well , this is gonna be the same as seven
09:03 and seven and $3.50 and you'll get a fairly close
09:07 answer . Okay ? So anyway , hopefully you are
09:10 good with those and they're nice and simple . Okay
09:13 . Any comments ? Any questions , please let me
09:15 know . Okay , see you then .
Summarizer

DESCRIPTION:

OVERVIEW:

Work out percentage discounts instantly! is a free educational video by tecmath.

This page not only allows students and teachers view Work out percentage discounts instantly! videos but also find engaging Sample Questions, Apps, Pins, Worksheets, Books related to the following topics.


GRADES:


STANDARDS:

Are you the Publisher?

EdSearch WebSearch